Jumper cable

ABSTRACT

A jumper cable with a clamp on each end of an insulated conductor, there being attached to this combination at the junction of the conductor and each of the clamps a peripheral helical flexure to relieve the strain on the junction by limiting the least radius attainable by bending the electrical connector adjacent to the junction.

A United States Patent G amson [is] 3,678,438 [451 July 18,1972

[ JUMPER CABLE [72] Inventor: Michael J. Gamson, 5449 Rimhurst, Glendara, Calif. 91740 [22] Filed: March 25, 1971 [21] Appl. No.: 128,032

[52] US. Cl. .,....339/29 B, 339/103 R, 339/200 P, V 339/255 P, 339/261 [51] Int. lolr 11/24 [58] Field of Search ..339/28, 29, 103, 200, 255, 339/260, 261, 58, 108

[56] References Cited UNITED STATES PATENTS 2,979,650 4/ l 961 Godshalk et al ..339/26l FOREIGN PATENTS OR APPLICATIONS 284,196 11/1952 Switzerland ..339/29 R Primary Examiner.loseph H. McGlynn Attorney-Angus & Mon

[57] ABSTRACT A jumper cable with a clamp on each end of an insulated conductor, there being attached to this combination at the junction of the conductor and each of the clamps a peripheral helical flexure to relieve the strain on the junction by limiting the least radius attainable by bending the electrical connector adjacent to the junction.

11 Claims, 3 Drawing figures JUMPER CABLE This invention relates to jumper cables of the class used in providing supplementary electrical energy to an automotive electrical system. I

The use of a jumper cable is known to anyone whose automobile battery has failed. It is customary for a tow truck to carry a well-charged battery, and to connect its terminals to the terminals of the disabled battery by means of a conductive cable having a clamp on each end. The clamps are customarily of the alligator type.

Examination of jumper cables which have been in use for a significant length of time, will show that most of them have a coating of friction tape or other insulating material to cover a break in the material, because at the junction of the clamp and the cable there have been imposed severe bending stresses of a cyclic nature which result in early failure by fatigue and work hardening. These jumper cables are expensive, and itis an object of this invention to provide a jumper cable which will last longer because its possible smallest radius adjacent to the clamps is limited.

A jumper cable according-to this invention includes a pair of clamps, one of which is attached to each end of an insulated electrical conductor. The electrical connection and structural joinder is made to one of the handles of each clamp. A flexure surrounds the junction of each clamp with the conductor, preferably having a helical construction with interlocked convolutions. There is a minimum radius of which the flexure can be bentwhen the convolutions are interlocked, and this feature limits the minimum radius of the conductor at and adjacent to the junction.

The invention will be fully understood from the following detailed description and the accompanying drawings in which:

FIG. 1 is a side elevation of one end of the presently preferred embodiment of the invention;

FIG. 2 is a cross-section taken at line 2-2 of FIG. 1; and

FIG. 3 is a side view, mostly in axial cross-section, of a portion ofFIG. l.

A jumper cable according to the invention is shown in FIG. 1. Only one end is shown, the other end (not shown) being identical to it. A flexible electrical conductor 11 is jacketed by insulating layer 12, and has two ends. Preferably, but not necessarily, the electrical conductor is stranded coppercoated aluminum wire twisted into a cable according to known practices. The material might instead be all copper or all aluminum. In any event, it is relatively flexible to a practicable degree, and is a good conductor of electricity.

At each end of the jumper cable there is a clamp 15 of the alligator type. It includes jaws 16 and 17 which are joined together at a hinge l8, and the jaws are biased closed by a spring 19. Handles 20, 21 are attached to and continuous with the jaws, and can open the jaws by being squeezed together. The spring closes the jaws when the squeeze on the handles is released.

As best shown in FIG. 3, handle has a channel 22 within which the electrical conductor is received and crimped, soldered or otherwise structurally and electrically attached thereto. Therefore, handle 20 and jaw 17 are hot. In this embodiment, both jaws (and handle 21) are hot. It is obvious, however, that only one handle and one jaw need be in conductive connection with the conductor.

A flexure 25, which is preferably helical in shape, has a plurality of convolutions, such as convolutions 26, 27, and surrounds the junction 28 of the clamp and of the conductor and extends for a significant distance both ways from the end of the handle. It is preferably in close embracing contact with the handle and securely fastened thereto. The convolutions of the helix may, if desired, be free from one another, but the objection to this arrangement is that with substantial effort it would still be possible to crimp the helix sharply enough to deform it, and thereby destroy the advantages of the invention. Accordingly, it is preferable for the convulutions to be interlocked, such as by means of providing a trough 29 at one edge of each into which an overhanging lip 30 depends. However, the usage of helices such as springs without adjacent convolutions locked together is within the scope of the invention. The

trough has a dimension of width 31 which can accommodate some sliding axial movement of the overhanging lip which is limited by shoulders 32, 33.

It will thereby be seen that the maximum flexure, meaning as a practical matter the achievement of minimum radius will occur when, at opposite sides of the flexure, the lip has contacted one shoulder and the lip at the opposite side has contacted the other shoulder. Preferably, a layer of insulation 34 surrounds the convolutions and includes flanges 35 which key into them to keep this layer of insulation in place. It will, however, be resilient so that it will not interfere with the bending of the flexure.

An insulating tube 36 surrounds the handle 20 and the flexure to the extent needed for a hand grip, it being desired to cushion the forces on the junction as much as possible and to give an adequate hand hold so the user will not touch any live portion of handle 20. A similar insulating tube 37 is formed on handle 21.

As is best shown in FIG. 2, the electrical conductor is preferably stranded, being composed of a plurality of strands 40. Each strand will preferably comprise the core 41 and a jacketing layer 42, the best example being an aluminum core with a copper jacket. Alternatively, the conductors could instead be solid copper or solid aluminum, or even steel if desired. However, steel will ordinarily be too heavy and too stiff. The advantage of utilizing stranded cable for this device is its ready flexing, which flexing does not occur with heavy solid conductors. The longitudinal shear sliding between the strands permits such ready bending.

It will now be observed that sharp bending of the conductor at and adjacent to its junction with the handle is avoided because the minimum bending radius is limited by the flexure which surrounds it, especially when adjacent convolutions are interlocked. The term junction" as used herein connotes the location where the end of the handle meets the conductor, and not a junction in the electrical semi-conductor sense of the word. Accordingly, it will be found that this device lasts many times the life time of standard jumper cables.

The attachment of the flexure to the handle can be accomplished in various ways, depending upon the structural characteristics desired. It can be squeezed onto the handle, deforming the flexure, or it might be threaded onto the handle utilizing the helices as threads. Alternatively, the handle could be crimped over the flexure.

A loose fit may exist between the flexure and the cable, it being unnecessary for a tight fit to be made between them. However, it will often be found desirable to make the fit fluid tight in order to keep out corrosive liquids.

This invention thereby provides a jumper cable with an enlarged life compared to existing devices and which is readily manufactured from standard parts.

This invention is not to be limited by the embodiment shown in the drawings and described in the description, which is given by way of example and not of limitation, but only in accordance with the scope of the appended claims. 1

lclaim:

1. A flexible jumper cable comprising: a flexible electrical conductor; an insulating layer surrounding said conductor; a pair of clamps, each clamp having a pair of jaws and a pair of handles attached to respective jaws, a hinge permitting the jaws to be opened by squeezing the handles together, and a spring biasing the jaws toward their closed position, at least one handle and jaw being electrically conductive and electrically connected to each other, said handle being structurally and electrically connected to the conductor at a junction so that there is a clamp at each of its ends, and electrical continuity exists from a jaw of one clamp to a jaw of the other clamp; a helical flexure surrounding said handle and that portion of the conductor adjacent to the handle, said flexure being structurally connected to said one handle, whereby to limit the bending of the conductor adjacent to the junction and handle; and insulation surround the flexure, and surrounding that portion of each of said handles which is intended to be contacted by the hand.

2. A jumper cable according to claim 1 in which the helical flexure includes a plurality of convolutions which are interlocked so as to establish a minimum limit to the radius to which the conductor can be bent adjacent to the junction.

3. A jumper cable according to claim 2 in which each convolution includes a helical trough bounded by a pair of axially spacedapart shoulders, and an overhanging lip depending into the trough of the next adjacent convolution, whereby abutment of the lip and of the shoulders limits the said bendmg.

4. A jumper cable according to claim 1 in which the said insulation includes a tubular layer surrounding said flexure.

5. A jumper cable according to claim 3 in which the insulation around the flexure is keyed into the convolutions.

6. A jumper cable according to claim 1 in which the conductor is stranded.

7. A jumper cable according to claim 6 in which the said one handle at least partially surrounds the end of said conductor.

8. A jumper cable according to claim 7 in which the helical flexure includes a plurality of convolutions which are interlocked so as to establish a minimum limit to the radius to which the conductor can be bent adjacent to the junction.

9. A jumper cable according to claim 8 in which each convolution includes a helical trough bounded by a pair of axially spaced-apart shoulders, and an overhanging lip depending into the trough of the next adjacent convolution, whereby abutment of the lip and of the shoulders limits the said bendmg.

10. A jumper cable according to claim 9 in which the said insulation includes a tubular layer surrounding said flexure.

11. Ajumper cable according to claim 10 in which the insulation around the flexure is keyed into the convolutions.

l III I I. 

1. A flexible jumper cable comprising: a flexible electrical conductor; an insulating layer surrounding said conductor; a pair of clamps, each clamp having a pair of jaws and a pair of handles attached to respective jaws, a hinge permitting the jaws to be opened by squeezing the handles together, and a spring biasing the jaws toward their closed position, at least one handle and jaw being electrically conductive and electrically connected to each other, said handle being structurally and electrically connected to the conductor at a junction so that there is a clamp at each of its ends, and electrical continuity exists from a jaw of one clamp to a jaw of the other clamp; a helical flexure surrounding said handle and that portion of the conductor adjacent to the handle, said flexure being structurally connected to said one handle, whereby to limit the bending of the conductor adjacent to the junction and handle; and insulation surround the flexure, and surrounding that portion of each of said handles which is intended to be contacted by the hand.
 2. A jumper cable according to claim 1 in which the helical flexure includes a plurality of convolutions which are interlocked so as to establish a minimum limit to the radius to which the conductor can be bent adjacent to the junction.
 3. A jumper cable according to claim 2 in which each convolution includes a helical trough bounded by a pair of axially spaced-apart shoulders, and an overhanging lip depending into the trough of the next adjacent convolution, whereby abutment of the lip and of the shoulders limits the said bending.
 4. A jumper cable according to claim 1 in which the said insulation includes a tubular layer surrounding said flexure.
 5. A jumper cable according to claim 3 in which the insulation around the flexure is keyed into the convolutions.
 6. A jumper cable according to claim 1 in which the conductor is stranded.
 7. A jumper cable according to claim 6 in which the said one handle at least partially surrounds the end of said conductor.
 8. A jumper cable according to claim 7 in which the helical flexure includes a plurality of convolutions which are interlocked so as to establish a minimum limit to the radius to which the conductor can be bent adjacent to the junction.
 9. A jumper cable according to claim 8 in which each convolution includes a helical trough bounded by a pair of axially spaced-apart shoulders, and an overhanging lip depending into the trough of the next adjacent convolution, whereby abutment of the lip and of the shoulders limits the said bending.
 10. A jumper cable according to claim 9 in which the said insulation includes a tubular layer surrounding said flexure.
 11. A jumper cable according to claim 10 in which the insulation around the flexure is keyed into the convolutions. 